Latent heat must be visible in climate communications

Tom Matthews*, Michael Byrne, Radley Horton, Conor Murphy, Roger Pielke Sr, Colin Raymond, Peter Thorne, Robert L. Wilby

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

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Abstract

Anthropogenic forcing is driving energy accumulation in the Earth system, including increases in the sensible heat content of the atmosphere, as measured by dry-bulb temperature—the metric that is almost universally used for communications about climate change. The atmosphere is also moistening, though, representing an accumulation of latent heat, which is partly concealed by dry-bulb temperature trends. We highlight that, consistent with basic theory, latent heat gains are outpacing sensible heat gains over about half of the Earth's surface. The difference is largest in the tropics, where global “hotspots” of total heat accumulation are located, and where regional disparities in heating rates are very poorly represented by dry-bulb temperatures. Including latent heat in climate-change metrics captures this heat accumulation and therefore improves adaptation-relevant understanding of the extreme humid heat and precipitation hazards that threaten these latitudes so acutely. For example, irrigation can lower peak dry-bulb temperatures, but amplify latent heat content by a larger margin, intensifying dangerous heat stress. Based on a review of the research literature, our Perspective therefore calls for routine use of equivalent temperature, a measure that expresses the combined sensible and latent heat content of the atmosphere in the familiar units of °C or K. We recognize that dry-bulb air temperature must remain a key indicator of the atmospheric state, not least for the many sectors that are sensitive to sensible heat transfer. However, we assert here that more widespread use of equivalent temperature could improve process understanding, public messaging, and adaptation to climate change.
Original languageEnglish
Article numbere779
Number of pages12
JournalWiley Interdisciplinary Reviews: Climate Change
Volume13
Issue number4
Early online date14 Apr 2022
DOIs
Publication statusPublished - 14 Jul 2022

Keywords

  • Climate change communication
  • Equivalent temperature
  • Extreme heat
  • Heat accumulation
  • Sensible heat

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